First, the bad news. Brown indicates 'Uninhabitable due to floods, drought or extreme weather'. Say goodbye to the Eastern Seaboard of the U.S., to Mexico and Central America, to the middle third of South America. In Africa, Mozambique and Madagascar are gone; Asia loses much of the Indian subcontinent, including all of Pakistan; Indochina is abandoned, as is most of Indonesia. As the map mentions, “The last inhabitants of (the South-west U.S. are) migrating north. The Colorado river is a mere trickle”; “Deglaciation means (Peru) is dry and uninhabitable”; and “Bangladesh is largely abandoned, as is South India. (In) Pakistan, isolated communities remain in pockets”.

Orange is not much better: 'Uninhabitable desert'. That's most of the U.S. and the rest of South America, almost the entirety of Africa and the southern halves of Europe and Asia. “Deserts have encroached on (Southern Europe), rivers have dried up and the Alps are now snow-free. Goats and other hardy animals are kept at the fringes”, the map predicts.

Red is for lands lost to the rising tide (assuming +4°C adds two metres to ocean levels). This may not seem a lot, but this is where populations are concentrated. In the U.S. for instance, counties directly on the shoreline constitute less than 10% of the total land area (not including Alaska), but account for 40% of the total population.

But there is a flipside. Light-green stands for food-growing zones, and compact high-rise cities. That's Western Antarctica, “unrecognisable now. Densely populated with high-rise cities”. New Zealand, sparsely populated in our time, will also be transformed into a high-density population centre. There will be a lot more room for this in the northern hemisphere: Siberia and Canada, where “reliable precipitation and warmer temperatures provide ideal growing conditions for most of the world's subsistence crops.” And the UK, Scandinavia, Greenland and northern Russia, which will be dotted with compact high-rise cities to “provide shelter for much of the world's population”.

A warmer climate could even lead to reforestation in certain areas of the world, including the Sahel and Western Australia. The regions abandoned to desertification are empty, but not useless: they will be used for solar farming (green dots) and geothermal energy (red dots). Giant wind farms off the coasts of South America, Alaska and in the North Sea will generate the remainder of the planet's energy needs.